Bulletin of the British Museum (Natural History)

98 BRIAN JOHN COPPINS
species in at least one case. Micarea intrusa {q.v.) possibly provides a link between the two
genera, and its inclusion in Micarea, rather than Scoliciosporum, is mainly on the grounds of
spore-type. The differences between the two genera are admittedly unclear and ill-defined at the
present time, and will certainly require re-appraisal as our knowledge of morphological,
ontogenetic, and phylogenetic aspects in the Lecideaceae increases.
A genus which may be closely related to both Micarea and Scoliciosporum is Strangospora
Massal.; it shares with them unsophisticated apothecial and thallus structures, and similar
ecological requirements. However, Strangospora differs in having polysporous asci with aseptate,
globose spores, although the asci do appear to be of the Lecanora-typQ. The monotypic
genus Steinia Korber is represented by S. geophana (Nyl.) Stein, whose small, black, immargin-
ate apothecia occurring on shaded substrate (soil, rotten wood, rocks, stones, etc.) are easily
confused in the field with those of some Micarea species. However, it is easily distinguished in
microscopical preparations by its 16-spored asci with globose spores, and simple, slender
paraphyses. In addition, its asci are not of the Lecanora-typQ, although their apices are each
provided with a broad, amyloid plug.
Micarea appears to have some affinities to Psilolechia Massal., and the two genera are
compared in the discussion of Psilolechia clavulifera (p. 376). Micarea may also be close to the
predominantly foliicolous Byssoloma Trevisan, but species of this latter genus have an excipulum
of loosely woven, hyaline, pachydermatous hyphae which spread laterally to form a
conspicuous white border to the apothecium. However, some specimens of B. subdiscordans
(Nyl.) P. James, when growing on bark, mosses, or rocks, do not have conspicuous whitebordered
apothecia, although the pachydermatous hyphae are clearly seen in sections of the
apothecia.
Lignicolous members of the 'Lecanora' symmicta group are occasionally confused with
Micarea species on account of their general appearance and excipulum structure. Their
excipular hyphae are radiating, richly branched and anastomosed and lax in K, although they
contrast markedly with the simple or sparingly branched paraphyses and do not give the
impression of being 'paraphysis-like'. This group further differs from Micarea in having dense
epithecial granules which dissolve in K and a generally different suite of Uchen substances (which
includes usnic acid and zeorin). Another seemingly distinctive group of species (but not yet
afforded generic status) that bears some close resemblances to Micarea is that containing such
species as Catillaria contristans, Lecidea limosa, and L. stenotera; for further discussion see
account oi Micarea assimilata (p. 115).
The apothecia of Vezdaea species are superficially similar to those of some species oi Micarea,
but differ in that their tissues are not bound by a gelatinous matrix and their asci have uniformly
amyloid walls and do not belong to the Lecanora-type; see Poelt & Dobbeler (1975).
There has been some confusion between Micarea and genera such as Arthonia Ach., and
Chrysothrix Mont., and also the Trapelia-\ike 'Lecidea' granulosa group. These all differ from
Micarea in not having Lecanora-typc asci (see 'Excluded taxa').
Suprageneric considerations
The formulation of a ± stable hierarchical classification of fungal (including lichen) taxa above
the rank of genus is unUkely to be achieved for some decades. A suprageneric classification for
the lichenized fungi has been attempted in recent years by, for example , Henssen & Jahns (1973)
and Poelt (19746). These schemes are extremely useful bases for further study but, as admitted
by their authors, contain very many uncertainties and points of conjecture, and should be
regarded as being of a very provisional nature.
Micarea has Lecanora-type asci and clearly belongs in the order Lecanorales and suborder
Lecanorineae as defined by Poelt (19746). My belief is that Micarea should be placed in the
Lecideaceae Chev. s. sir. (i.e. confined to species with Lecanora-type asci), with the provision
that the real differences (if any) with that family and the Lecanoraceae Fee need to be explored.
For the time being (at least) I cannot accept the 'Micareaceae Vezda ad int.' (Poelt, 19746: 627;
Eriksson, 1981), although it may be possible to formally define this family name in the future as
knowledge and taxonomic concepts in the Lecanorales increases and advances.